Andy Burnham says he is “confident” PC Andrew Harper’s killers can be excluded from the government’s early release scheme, as outcry over the case grows.

The prime minister has ordered the justice secretary to find a way to bar Jessie Cole and Albert Bowers, who were jailed for 13 years for manslaughter in 2020, from early release.

He said a plan to prevent more prisoners from being freed long before the end of their sentences would be presented to Parliament in September.

The move comes after days of pressure to exclude Harper’s killers from the scheme, which is aiming to free about 5,000 offenders in England and Wales to make space in overcrowded jails.

Harper’s mother, Debbie Adlam, told the BBC she was in “turmoil” following conflicting reports about whether two of her son’s killers would be released from prison early, describing the handling of the situation as a “hash”.

Conservative shadow home secretary Chris Philp accused Burnham and Labour of “re-traumatising victims and their families with their constant U-turns”.

Burnham’s position on early releases has shifted since last week, when he said there was “nothing more” he could do without risking the collapse of the prison system.

Burnham launched a review of the scheme after he became prime minister and last week, he announced that some prisoners convicted of rape, serious child sex and other grooming offences would be barred from early release.

In an article published last week, external, Burnham said he “wanted to go even further” but had “pushed to the very limits of what is possible to do”.

He added: “I know I can look people in the eye and say to them there is nothing more I could have asked for without risking the prison system reaching capacity and collapsing within months.”

But on Tuesday, Burnham insisted he had never accepted “there was nothing more that could be done” to prevent the early release of more offenders, including Harper’s killers.

Burnham told reporters “nothing has changed”. He added: “I came into office and started pushing on this issue, and I have pushed every single day in office”.

Burnham said he would seek to hold talks with other political parties to build “consensus” on the approach to early releases.

The government’s early release scheme aims to address a severe overcrowding crisis in jails, where useable capacity is almost at 100%.

The number of places in jails in England and Wales has not kept pace with the significant rise in the prison population in recent decades under successive governments.

Ministers have said prison spaces might run out as soon as October.

To make more space in prisons, the Starmer government changed the law to give it the ability to release some offenders earlier than they would otherwise have been.

The release point for these prisoners will move from 40% or half of their custodial term to one third for some offenders, and from two thirds to half for others.

Since taking office, Burnham made exemptions for those convicted of some serious offences, but not manslaughter, prompting a backlash and pressure to block the release of Harper’s killers.

Harper, 28, from Wallingford, Oxfordshire, died in 2019 when he was dragged behind the getaway car of three teenagers who had fled the scene of a quad bike theft in Berkshire.

Two of his killers, Cole and Bowers, will become eligible to be freed from jail next year under the release scheme as it stands.

The third man jailed for the manslaughter of Harper – the vehicle driver Henry Long – was given a longer 16-year jail term and cannot be considered for early release.

It is not yet clear how the government will prevent Cole and Bowers from being treated the same as other prisoners with similar sentences.

If ministers said, for example, that prisoners with manslaughter convictions could not be considered for the scheme, that would have an instant impact on many other inmates.

Last week, Burnham also ordered an “urgent” review to identify any grooming gang members who may be eligible to be freed from jail early.

The government has not confirmed whether the review will lead to the prevention of any early releases of offenders convicted of grooming-related crimes.